A Complementary Gray Code Like Double N-Step Phase Shift Method Without Gray Code Fringe Images

Abstract

The complementary Gray code double N-step phase shift method is widely used because of its high detection accuracy and good robustness. However, phase unwrapping methods have the problem of low detection efficiency. In order to solve above problem, this paper proposes a complementary Gray code like double N-step phase shift method without Gray code fringe images. Firstly, the wrapped phases of the different groups of phase shift fringe images are obtained, then we get the phase difference and the fused wrapped phase, and the phase difference is converted into Gray code series. Finally, the unwrapped phase of the measured target is obtained by combining the fused wrapped phase and the Gray code series. This method in this paper improves the detection efficiency. To verify the effectiveness of method proposed in this paper, the method is compared with the complementary Gray code double N-step phase shift method, the complementary Gray code 2N-step phase shift method and the phase derivative variance method. The experimental results show that the method in this paper could effectively obtain the high-precision unwrapped phase, and the efficiency is 33.3% higher than the complementary Gray code double N-step phase shift method and the complementary Gray code 2N-step phase shift method.

Keywords

• Double N-step phase shift method
• phase difference
• complementary Gray code like
• fused wrapped phase
• phase unwrapping